Parallel scheduling of multilayered media

ABSTRACT

Multi-link transportation of media, video and other data of the type having multiple layers, streams and/or encodings is contemplated. The multi-link transportation may be facilitated with a scheduler configured to schedule the various layers, streams, encodings, etc. for transportation over selectable communication links, such as based on reliability, capacity and/or other operating characteristics.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/271,791, filed Feb. 9, 2019, which application is a continuation ofU.S. application Ser. No. 15/368,738 filed Dec. 5, 2016, which in turnis a continuation of U.S. application Ser. No. 14/558,995 filed Dec. 3,2014, which in turn claims the benefit of U.S. provisional applicationNo. 61/912,733 filed Dec. 6, 2013, the disclosures and benefits of whichare hereby incorporated in their entireties by reference herein.

TECHNICAL FIELD

The present invention relates to facilitating transportation of media,video and other data of the type having multiple layers, streams and/orencodings, such as but not necessarily limited to facilitating paralleltransport scheduling of such multilayered media across multiplecommunication links.

BACKGROUND

Any number of techniques, protocols, specifications and the like existto facilitate generating media in an electronically transmissible form.The electronically transmissible media may be generated by encoding,processing or otherwise manipulating an original content into anelectronic form suitable for entirely or partially representing theoriginal content. In the case of video, such as that formatted inaccordance with Moving Picture Experts Group (MPEG) version 2 (MPEG-2)or version 4 (MPEG-4), the disclosures of which are hereby incorporatedby reference in their entireties, the original content may be encodedinto a plurality of layers/streams to generate the media, which may bereferred to as multilayered media. MPEG encoders may be configured toproduce multilayered media by encoding the original content intointra-coded pictures (I-frames), predicted pictures (P-frames) andbi-predictive pictures (B-frames). One non-limiting aspect of thepresent invention contemplates facilitating transport of multilayeredmedia, video and other data of the type having multiple layers, streamsand/or encodings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a system for transporting multilayered media inaccordance with one non-limiting aspect of the present invention.

FIG. 2 illustrates a flowchart of a method for parallel scheduling ofmultilayered media in accordance with one non-limiting aspect of thepresent invention.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

FIG. 1 illustrates a system 10 for transporting multilayered media inaccordance with one non-limiting aspect of the present invention. Thesystem 10 may be configured to facilitate transporting virtually anytype of media, including video, audio, pictures, images, etc. and is forexemplary non-limiting purposes predominately described with respect tofacilitating transport of video encoded according to MPEG and deliveredwithin a transport stream from a source 12. The MPEG encoded video mayinclude a plurality of layers to facilitate representing the originalcontent as a plurality of video frames, optionally with a layer for eachtype of encoding, i.e. a layer for the I-frames, a layer for theP-frames and a layer for the B-frames. The I-frames may correspond withthe fundamental frames for any image and come in at a lower rate(frequency), the P-frames may be generated at a higher rate than theI-frames and may be additive to the I-frames to add more resolution andsimilarly the B-frames may be generated at a higher rate than theP-frames to add more resolution A transmitter 14 may be configured inaccordance with the present invention to process the transport stream,or more particularly one or more of the layers therein, for multi-linktransport to a receiver 16.

The transmitter 14 may include a demultiplexor 18 to demultiplex orotherwise recover one or more layers/streams included within thetransport stream for output to a scheduler 20, which for exemplarypurposes is shown to correspond with recovery of a plurality of feeds22. The scheduler 16 may be configured to schedule the plurality offeeds 22 for transport over a corresponding one or more of a pluralityof links 24. The transmitter 14 may include a controller 30 configuredto facilitate controlling the demultiplexor 18 and the scheduler 20 andto otherwise facilitate the operations contemplated herein, such as inaccordance with a plurality of non-transitory instructions includedwithin a computer-readable medium associated with the transmitter 14.One non-limiting aspect of the present invention contemplates thecontroller 30 being operable to assess operating conditions orcharacteristics of the plurality of links 24 and to schedule transportof the feeds 22 (I-frames/layer, P-frames/layer, B-frames/layer) overthe links 24 as a function thereof. The capability to selectively managethe links 24 used to subsequently transport the video may be beneficialin enabling a service provider or other entity operating the transmitter14 to maximize capacity, reliability, throughput and/or quality ofservice (QoS).

The transport scheduling contemplated by one non-limiting aspect of thepresent invention may be performed in a parallel manner wherebydifferent portions of the transport stream may be simultaneouslytransported over two or more of the links 24. The parallel processingmay take many forms and is illustrated for non-limiting purposes tocorrespond with an exemplary scenario where the I-frames, P-frames andB-frames, or corresponding portion/layer/stream 22 of the transportstream, are respectively transported over a first link, a second linkand a third link of the plurality of links 24. The links 24 aregenerically shown to correspond with any communication medium suitablefor transporting the various layers/streams and may be physically and/orlogically distinct and comprised of some combination of wireless and/orwireline communication mediums. The scheduler 20 may include a pluralityof interfaces 32, 34, 36 operable to facilitate communications with acorresponding link, optionally having capabilities associated with asignal processor, end station, eNodeB, base station, cable modem, Wi-Firadio or other device having capabilities sufficient to facilitate thecontemplated multi-link communications, including those suitable tofacilitating Multiple-Input Multiple-Output (MIMO) communications, suchas that associated with U.S. patent application Ser. Nos. 14/181,640,14/181,641, 14/181,643 and 14/181,645, the disclosures of which arehereby incorporated by reference in their entireties herein.

The transport of one or more layers 22 over one or more links 24 mayrequire processing, addressing or other manipulations to be performed atthe corresponding interface. The interfaces 32, 34, 36 may be configuredto support device Time Division Multiple Access (TDMA), OrthogonalFrequency Division Multiplexing (OFDM), Orthogonal Frequency DivisionMultiple Access (OFDMA), Single Carrier Frequency Division MultipleAccess (SC-FDMA), Data Over Cable Service Interface Specifications(DOCSIS) 3.x, Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wi-Max,Wi-Fi, Digital Video Broadcasting-Terrestrial (DVB-T), Digital VideoBroadcasting-Handheld (DVB-H), etc., the disclosures of which are herebyincorporated by reference in their entireties. The interfaces 32, 34, 36may optionally be configured to support a particular type of medium,e.g. one of the interfaces may be an LTE interface and another one ofinterfaces may be a Wi-Fi interface or a DOCSIS interface. Thecontroller 30 and/or the interfaces may be responsible for addressingmessages and otherwise complying with transmission requirements of theparticular network. One non-limiting aspect of the present inventioncontemplates packets used to transport the layers/frames to be addressedaccording to Internet Protocol (IP), optionally with all of the packetshaving the same source and destination addresses due to the packetsemanating from the same transmitter 14 and being received at the samereceiver 16 or device associated with the receiver 16.

FIG. 2 illustrates a flowchart 40 of a method for parallel scheduling ofmultilayered media in accordance with one non-limiting aspect of thepresent invention. Block 42 relates to determining multilayered mediadesired for transport, such as in response to a transmission requestreceived from a network scheduler or user input sufficient foridentifying the media desired for transport and a destinationaddress/location. The multilayered media may comprise or consist of anytype of media having multiple layers, streams, portions or otheridentifiable units susceptible or otherwise amenable to the multi-linktransport contemplated herein, such as MPEG-2, MPEG-4, H.263+ and DCTbased encoding schemes. The portions of the media amenable to multi-linktransport are hereinafter referred to for exemplary non-limitingpurposes as layers, which may be identified to a transmitter as afunction of information included with the corresponding transportrequest. Some media desired for transport may include more layers thanother types of media and/or some media may include layers that changeover time, e.g., a layer at a beginning of a particular type of mediamay not be present at an ending of the media. While not intending tolimit the scope and contemplation of the present invention, the mediamay be a television program, movie, etc. formatted according to MPEGwhereby the contemplated layers may be demarcated according to I-frames,B-frames, and P-frames.

Block 44 relates to determining links available for media transport. Thelinks may be determined at a physical level, e.g., one link for Wi-Fi,one link for LTE and one link for DOCSIS, and/or the links may bedetermined at a logical or virtual level, e.g., one physical connectionmay support multiple links through virtual networks, tunnels, etc. Theavailable links may also be determined as a function of operatingcharacteristics, such as capacity, throughput, wireless spectrum,subscription rights and other variables tending to cause availability tobe transient. The capacity or available capacity of a particular linkmay vary over time such that at one point in time the link is noted asbeing available while at another point in time the link may be noted asunavailable if overloaded. Similar determinations may be based onthroughput or other operating characteristics, e.g., a physicallyavailable link may be determined to be logically or functionallyunavailable if the throughput is below desired operating levels orlicensing spectrum is temporarily unavailable. Optionally, the expectedoperating conditions over an expected length of the transport (e.g.movie run-time) may be analyzed to ensure the link remains availablethroughout a period of time needed to complete transport. In the event alink should become unavailable during transport, one of the other linksmay be engaged to make up for the deficiency.

Block 46 relates to demultiplexing the media desired for transport. Thedemultiplexing may include separating the media into a plurality offeeds associated with the different layers, e.g., the exemplary MPEGformatted video may be demultiplex into an I-Frame feed, a P-frame feedand a B-frame feed. The number of feeds or the amount of demultiplexingmay correspond with the number of links selected to be available fortransport. The demultiplexing may be skipped or delayed until a new linkbecomes available in the event a single link is determined or thedemultiplexing may include generating a feed having multiple layerswithin it if the number of layers is greater than the available numberof links (the I-frames and P-frames may be communicated over the samelink as a single feed). The demultiplexing need not be stagnantthroughout the corresponding transport and may be varied to more or lessfeeds/links as link operating characteristics change. The demultiplexingmay include adding addressing information, timestamps or other datanecessary to facilitate multiplexing the feeds back together at thereceiver in a manner sufficient to enable desired playback. Themultiplexing may also add delay, stuffing/blank frames and other datasufficient to synchronize the sequence of frames arriving at thereceiver to compensate for transmission delays or inconsistenciesattendant to the various links.

Block 48 relates to scheduling transport of the multilayered media. Thescheduling may correspond with controlling the interfaces associatedwith each of the links selected for transport to communicate packets,signals or other segments depending on the operating characteristics ofthe corresponding link. The transport may be scheduled such that areceived sequence of the frames following transport to the receiver isapproximately equal to a multiplexed sequence of the frames whenreceived at the demultiplexor, e.g., the media when received at thereceivers is ordered in approximately the same order as when received atthe demultiplexor. Optionally, the scheduler may facilitate transport ofthe media according to a transport sequence having delay, blanks, etc.added to compensate for transmission inequalities or latencies of thelinks. The transport sequence may differ from the multiplexed sequenceby an amount or order sufficient for enabling the media to arrive at thereceiver at the received sequence. The transport scheduling may alsoinclude facilitating the use of common source and destination addressesand/or notifying the receiver of various transmission related parametersnecessary to facilitate the desired receipt and playback of the media.

As supported above, one non-limiting aspect of the present inventionaddresses issue of maximizing network user capacity by optimizing thedelivery of multimedia to the maximum number of users, which may be isachieved by coupling a scheduling algorithm with the multilayer encodingsupported by encoders such as MPEG4 to deliver the various layers overdifferent links. In multilayer encoding, the source (video or audio) isencoded into multiple layers/streams and one aspect of the presentinvention takes advantage of the properties of the encoding layers (forexample the I/P/B frames) to maximize capacity (number of users) ofvideo delivery when the traffic in a network can be carried over twodifferent technologies; for example: A hybrid of a wireless network anda HFC network, an HFC network running different versions of the DOCSISspecification (ex. D3.1 and D3.0, or D3.0 and D2.1, etc. . . . ) Thenetwork may be composed of two (or more) physical or logical networks asdescribed above; the first network (Network A) has the highestreliability or most penetration to the largest number of users, and thesecond network (Network B) has either less reliability or penetration.This concept is not limited to two physical or logical networks and canbe extended to any number of networks.

To maximize capacity (number of users) of the video delivery, theI-frames may be scheduled for transport over the most reliable path ortechnology with most user penetration (Network A), P frames can bedelivered over network A or B or a combination of both based onavailable capacity, and the B-frames over Network B. One example mayrelate to a hybrid HFC/wireless network where the I-frames and P-framesmay be delivered over the HFC network and the B-frames may be deliveredover the wireless network based on capacity availability. In thissituation, the HFC network traffic may be alleviated (from the B-frameloading) allowing other applications/data to use the path, the largestnumber of users will have the video delivered to them and the B-framesmay be delivered opportunistically over the wireless network based onnetwork loading such that video capacity is maximized (video deliveredto largest number of users) and the HFC traffic may be alleviatedallowing other applications to run. Another example may relate to aDOCSIS 3.1 and DOCSIS 3.0 networks where initial network deployments mayhave a more pervasive DOCSIS3.0 deployment and a gradually growing ofD3.1 deployments. In this scenario, the I-frames and P-frames can bedelivered over D3.0 and B frames can be delivered over D3.1 according toavailable capacity. Similar to above, this may guarantee that themaximum number of users are receiving the required video content, andbased on available capacity or user tier rates, the B-frames can bedelivered to the possible users to provide more resolution and videofidelity.

One non-limiting aspect of the present invention maximizes networkcapacity and utilization among subscribers while guaranteeing multimediacontent delivery to the maximum number of users and allowing otherapplications/traffic to use and share the network. This may become evenmore crucial when video over IP becomes more prevalent. While deliveryof the multilayer encoded video/audio over the same network withoutdifferentiation is contemplated, this can create large network trafficand limit the ability of other applications to share the network. Timingwork across multiple networks may be coordinated across correspondingschedulers/interfaces. The schedulers may be in the same transmitter andsynchronization between them may be managed so that packets going onLink B do not arrive at destination beyond a certain timeframe comparedto frames on link A, as doing so would cause them to be essentiallyuseless and the scheduler is better off dropping the packets. Thereceiver may have knowledge that it is receiving packets from twodifferent links, and thus possibly over two different IP addresses, andwill be able to identify that the packets originate from the same sourcebased on IP address/Port number. Given that the source of the frames arethe same source (video source), there is no actual need to have multipleIP addresses given that they are originating from the same transmitter,IP address can be the same; as the goal of the IP address is to identifythe source and the destination; but given that the links are different,the MAC addresses would be different. Several algorithms can bedeveloped around the capabilities enabled with the present invention.The I-frame could be scheduled be on the network with most penetrationor reliability or penetration×reliability to reach the largest number ofusers as it is a base frame. For the remainder of the frames, thescheduling can be based on latency, congestion, throughput, etc. and maydepend on network operator needs and preferences.

One non-limiting aspect of the present invention contemplates anenhanced service delivery using Hybrid Wireless/Coax links. Thecustomers (end users), may evaluate their link using two basicmetrics: 1. Bits per second (speed); and 2. Quality (Video quality forstreaming, downtime, etc. . . . ) For a certain deployment, in order toimprove the above two metrics without a change to the underlyingphysical network, the one aspect of the present invention contemplatesan evolution of the technology being transported on the links (e.g.DOCSIS 2.0, DOCSIS 3.0, DOCSIS 3.1, etc. . . . ), which may in somecircumstances be unable to address the one constraint associated withthe underlying network infrastructure, e.g., the coax part of theirnetwork. Another aspect of the present invention contemplates augmentingthe coax network with wireless links to create a Hybrid RF/Coax networkwhere the wireless and coax networks intelligently cooperate indelivering the data to the users whereby data is delivered usingwireless and coax, rather than wireless or coax. Given that the coax andthe wireless channels can be considered to be orthogonal channels, thismay provide huge flexibility in optimizing service delivery to the enduser. Per Shannon's equations, adopting this solution may provide anaggregate capacity greater than the sum of the capacities of bothsystems running independently.

The contemplated cooperation between the wireless and coax can occur atmultiple layers:

-   -   1. Physical layer: The wireless can possibly provide        opportunistically high throughput links but with higher        susceptibility to channel conditions which impacts performance,        while the coax links provide a higher availability and        reliability but with possibly lower rates. Cooperation between        the wireless and the Coax link can occur in multiple ways: a. By        jointly optimizing the modulation and coding across both        channels; and b. Interference/Noise management on the link by        load shifting and thus improving SNR, the throughput/QoS can be        enhanced to the end user.    -   2. MAC layer: Intelligent multi-link Scheduling, to decide on        which link to schedule certain flows based on the QoS        requirements and link loading.    -   3. Cross layer MAC-PHY optimization: as given in scenario 1;        load balancing across both channels can yield improved signal        quality across the channels by reducing the overall noise, or        scheduling decisions based on PHY channel conditions and        availability.

One physical layer scenario may include a deployment of N users who arebeing supported by the hybrid network where a subset M require a high USthroughput while the N-M have a low US throughput requirement. Byshifting the M-N users to the wireless links, the present invention canreduce the noise on the US Coax link due to noise funneling, whicheffectively increases the US SNR for the M users without impacting theN-M user experience. One MAC layer scenario may include a deployment ofN users who are being supported by the hybrid network where a subset Mrequire average throughput but low latency SLA, while the remainingusers are requiring a high bursty throughput without stringentrequirements for latency SLA (ex. Browsing, FTP downloads, etc. . . . ).The MAC can then decide to schedule the M users on the wireless links,thus protecting them from queuing delays that can arise from the otherhigh throughput users. One cross-layer scenario may include videodelivery over hybrid network using MPEG4 where a MAC scheduler candecide to schedule the I and P frames over the Coax link thusguaranteeing the delivery of the basic video frames, while deciding toschedule the B frames over the wireless link, which can provide theenhanced video quality if the link loading conditions allow.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A non-transitory computer-readable medium havinga plurality of non-transitory instructions executable with a processorof a server to facilitate transport of content to a client over aplurality of links when the content is encoded according to a pluralityof encodings, the non-transitory instructions being sufficient for:identifying the content to be encoded according to at least a firstencoding and a second encoding of the plurality of encodings;identifying at least a first link of the plurality of links to beavailable for transporting the first encoding to the client and a secondlink of the plurality of links to be available for transporting thesecond encoding to the client; determining first parameters for thefirst link and second parameters for the second link, the first andsecond parameters respectively representing streaming characteristicsassociated with transport of the content over the corresponding firstand second link; and communicating information derived from the firstand second parameters to the client to facilitate the client accessingthe content when transported over the first and second links.
 2. Thenon-transitory computer-readable medium of claim 1 further comprisingnon-transitory instructions sufficient for: deriving from the first andsecond parameters a first throughput of the first link and a secondthroughput of the second link; and including as at least part of theinformation detail of the first and second throughputs, the detail beingsufficient for the client to correspondingly determine whether either ofthe first and second links is incapable of reliably supporting transportof the content.
 3. The non-transitory computer-readable medium of claim1 further comprising non-transitory instructions sufficient forincluding as at least part of the information a recommendation, therecommendation indicating: the first parameters to be one of appropriateand inappropriate for the client to access the first encoding over thefirst link; and the second parameters to be one of appropriate andinappropriate for the client to access the second encoding over thesecond link.
 4. The non-transitory computer-readable medium of claim 1further comprising non-transitory instructions sufficient for: receivinga request from the client associated with accessing the content; andallocating capacity for network elements of the first and second linksto facilitate meeting the request.
 5. The non-transitorycomputer-readable medium of claim 4 further comprising non-transitoryinstructions sufficient for allocating the capacity by limiting anability of applications to contemporaneously share with the client thenetwork elements needed to support transport of the content to theclient.
 6. The non-transitory computer-readable medium of claim 4further comprising non-transitory instructions sufficient fordetermining the capacity based on round trip time (RTT) specified in therequest to complete transport of the content.
 7. The non-transitorycomputer-readable medium of claim 1 further comprising non-transitoryinstructions sufficient for transmitting the first and second encodingsas plurality of Internet Protocol (IP) packets issued from the server.8. The non-transitory computer-readable medium of claim 1 furthercomprising non-transitory instructions sufficient for transmitting thefirst and second encodings from the server in accordance with HypertextTransfer Protocol (HTTP).
 9. The non-transitory computer-readable mediumof claim 1 further comprising non-transitory instructions sufficientfor: deriving from the first and second parameters a first throughput ofthe first link to be less than a second throughput of the second link;selecting an order for transmission of the first and second encodingsfrom the server as a function of the first and second parameters; addingsynchronization data to the second encoding to compensate for the firstthroughput being less than the second throughput, including determiningan amount and/or frequency of the synchronization data to beproportional to a difference between the first throughput and the secondthroughput such that the client plays back the content withoutre-playing and without missing the content when switching from the firstlink to the second link during playback; and including as at least partof the information detail sufficient for apprising the client of thesynchronization data.
 10. The non-transitory computer-readable medium ofclaim 9 further comprising non-transitory instructions sufficient addingthe synchronization data as timestamps sufficient to facilitate relatingin time a first sequence of first segments of the first encodingrelative to a second sequence of second segments of the second encoding.11. The non-transitory computer-readable medium of claim 9 furthercomprising non-transitory instructions sufficient for delayingtransmission of one or both of the first and second encodings tocompensate for inequalities or latencies between the first and secondlinks.
 12. The non-transitory computer-readable medium of claim 9further comprising non-transitory instructions sufficient for: receivingthe content at the server within a content stream, the content streamomitting the synchronization data; encoding the content stream at theserver according to a first type of encoding to generate the firstencoding; and encoding the content stream at the server according to asecond type of encoding to generate the second encoding, the second typediffering from the first type.
 13. The non-transitory computer-readablemedium of claim 12 further comprising non-transitory instructionssufficient for encoding according to the first and second types suchthat the second encoding is at a greater bit rate than the firstencoding.
 14. The non-transitory computer-readable medium of claim 1further comprising non-transitory instructions sufficient for:determining the first and second parameters to represent inequalitiesand/or latencies associated with the first and second links; selectingan order for transmission of the first and second encodings from theserver as a function of the first and second parameters; adding stuffingto the first encoding when being transported from the server tofacilitate arrival at the client in the order, the stuffing beingsufficient for increasing a total amount of data necessary to facilitatetransport of the first encoding; and including as at least part of theinformation detail sufficient for instructing the client to discarded orignore the stuffing during playback of the content.
 15. Thenon-transitory computer-readable medium of claim 1 further comprisingnon-transitory instructions sufficient for: determining the first andsecond parameters to represent inequalities and/or latencies associatedwith the first and second links; selecting an order for transmission ofthe first and second encodings from the server as a function of thefirst and second parameters, the order relating in time the firstencoding relative to the second encoding so as to arrive at the clientin a manner matching a prior order that the first and second encodingswere received at the server; adding synchronization data to transmissionof one or both of the first and second encodings such that the first andsecond encodings arriving at the client in the prior order, thesynchronization data being independent of data included as part of thecontent; and including as at least part of the information detailsufficient for apprising the client of the synchronization data.
 16. Aserver for transporting media to a client, the server comprising: anencoder for separately encoding the media into at least a first encodingand a second encoding, the second encoding being of a second typedifferent from a first type of the first encoding; a first interface fortransporting the first encoding over a first link and a second interfacefor transporting the second encoding over a second link, the second linkbeing physically and/or logically distinct from the first link; acontroller having a plurality of non-transitory instructions executablewith a processor associated therewith to facilitate transport of themedia, the non-transitory instructions being sufficient for: i)assessing suitability of the first and second links to respectivelyfacilitate transport of the first and second encodings; and ii)messaging the client regarding the suitability to facilitate the clientarbitrating between the first and second links when subsequentlyrequesting transport of the media.
 17. The system of claim 16 whereinthe non-transitory instructions of the controller are sufficient forrepresenting the suitability within a message having informationsufficient for indicating one or more of capacity, throughput, wirelessspectrum and subscription rights for each of the first and second links.18. The system of claim 16 wherein the non-transitory instructionsassociated with the controller are sufficient for: addingsynchronization data to the first encoding to facilitate the clientswitching playback of the media from the first encoding to the secondencoding without interruption, the synchronization data includingstuffing and/or blanks to compensate for transmission inequalities orlatencies between the first and second links; and messaging the clientto discard or ignore the stuffing and/or blanks.
 19. A method fortransporting content from a server to a client when the content isavailable in a plurality of encodings, the method comprising:determining capacity for network links available between the server andclient to transport the plurality of encodings; and messaging the clientof the capacity with detail sufficient for the client to requesttransport of the content over the network links having capacitysufficient to transport the corresponding encoding from the server tothe client.
 20. The method of claim 19 further comprising: receiving arequest from the client to transport a first encoding of the pluralityof encodings from the server to the client over a first link of thenetwork links contemporaneously with transport of a second encoding ofthe plurality of encodings from the server to the client over a secondlink of the network links; scheduling transport of the content to theclient in response to the request such that segments comprising each ofthe first and second encodings arrive at the client in an order,including specifying data to be added to the first encoding when beingtransported from the server to increase a size of the first encoding tocompensate for the capacity indicating throughput inequalities of thefirst and second links; and messaging the client regarding the data withdetail sufficient for the client to facilitate switching playback of themedia from the first encoding to the second encoding withoutinterruption.